Felsic Magmatism and U Deposits
-
Upload
lubomira-macheva -
Category
Documents
-
view
249 -
download
1
Transcript of Felsic Magmatism and U Deposits
-
8/13/2019 Felsic Magmatism and U Deposits
1/62
Manuscrit accept / Accepted manuscript
Felsic magmatism and uranium depositsGisements duranium et magmatisme felsiqueMichel CUNEY
Reu le /Received date: 09/05/2013Accept le /Accepted date: 14/10/2013
Prire de citer larticle de la faon suivante / Please cite this article as:
CUNEY M. (2014). Felsic magmatism and uranium deposits Bull. Soc. gol. Fr. 185, 2 (sous presse)
-
8/13/2019 Felsic Magmatism and U Deposits
2/62
1
Felsic magmatism and uranium deposits
Gisements duranium et magmatisme felsique
Michel Cuney
GoRessources, CNRS, CREGU, Universit de Lorraine, BP 239
54506, Vandoeuvre les NANCY Cedex, France
mailto:[email protected]:[email protected]:[email protected] -
8/13/2019 Felsic Magmatism and U Deposits
3/62
2
Plan dtaill
Key wordsABSTRACT
Mots clsRESUME
INTRODUCTION
THE DIFFERENT TYPE OF URANIUM-RICH IGNEOUS ROCKS
Propos ed classi f icat ion
Peralkal ine igneous rock s
Metalumin ous hig h-K calc-alkaline igneous rocks
Peraluminous igneous rock s
Anatect ic pegmatoids
URANIUM FRACTIONATION IN THE EARLY EARTH
Early Arch ean magm atic rock s
The first uranini te bearing granites
Genetic models for the Arch ean high-K granites
The first peraluminou s uranini te bearing igneous rock s
The first peralkal ine igneous ro cks
RELATIVE URANIUM FERTILITY OF URANIUM-RICH IGNEOUS ROCKS
Peralkal ine igneous rock s
High-K calc-alkal ine igneous rock s
Peraluminous igneous rock s
RELATIONS BETWEEN URANIUM DEPOSITS AND FELSIC IGNEOUS ROCKS.
Magmatic deposits
Hydroth ermal deposits
Olymp ic Dam deposit
Other deposit types
CONCLUSIONS
REFERENCES
Tables 1 and 2
Figure captions
Figures 1 to 4
Calibrage : 14 895 mots, 98 400 caractres, espaces et signes compris ~14 pages
-
8/13/2019 Felsic Magmatism and U Deposits
4/62
3
Key words: Uranium, granite, acidic volcanic rock, geochemistry, ore deposits, accessory
minerals
ABSTRACT: Uranium strongly incompatible behavior in silicate magmas results in its
concentration in the most felsic melts and a prevalence of granites and rhyolites as primary U
sources for the formation of U deposits. Despite its incompatible behavior, U deposits
resulting directly from magmatic processes are quite rare. In most deposits, U is mobilized by
hydrothermal fluids or ground water well after the emplacement of the igneous rocks. Of the
broad range of granite types, only a few have have U contents and physico-chemical
properties that permit the crystallization of accessory minerals from which uranium can be
leached for the formation of U deposits. The first granites on Earth which crystallized
uraninite appeared at 3.1 Ga, are the potassic granites from the Kaapval craton (South
Africa) which were also the source of the detrital uraninite for the Dominion Reef and
Witwatersrand quartz pebble conglomerate deposits. Four types of granites or rhyolites can
be sufficiently enriched in U to represent a significant source for the genesis of U deposits:
peralkaline, high-K metaluminous calc-alkaline, L-type peraluminous ones and anatecticpegmatoids. L-type peraluminous plutonic rocks in which U is dominantly hosted in uraninite
or in the glass in their volcanic equivalents represent the best U source. Peralkaline granites
or syenites represent the only magmatic U-deposits formed by extreme fractional
crystallization. The refractory character of the U-bearing minerals does not permit their
extraction at the present economic conditions and make them unfavorable U sources for
other deposit types. By contrast, felsic peralkaline volcanic rocks, in which U is dominantly
hosted in the glassy matrix, represent an excellent source for many deposit types. High-K
calc-alkaline plutonic rocks only represent a significant U source when the U-bearing
accessory minerals [U-thorite, allanite, Nb oxides] become metamict. The volcanic rocks of
the same geochemistry may be also a favorable uranium source if a large part of the U is
hosted in the glassy matrix. The largest U deposit in the world, Olympic Dam in South
Australia is hosted by highly fractionated high-K plutonic and volcanic rocks, but the origin of
-
8/13/2019 Felsic Magmatism and U Deposits
5/62
4
the U mineralization is still unclear. Anatectic pegmatoids containing disseminated uraninite
which results from the partial melting of uranium-rich metasediments and/or metavolcanic
felsic rocks, host large low grade U deposits such as the Rssing and Husab deposits in
Namibia.
The evaluation of the potentiality for igneous rocks to represent an efficient U source
represents a critical step to consider during the early stages of exploration for most U deposit
types. In particular a wider use of the magmatic inclusions to determine the parent magma
chemistry and its U content is relevant to evaluating the U source potential of sedimentary
basins that contain felsic volcanic acidic tuffs.
Mots cls: Uranium, granite, roche volcanique acide, gochimie, gisements, minraux
accessoires
RESUME : Luranium a un comportement incompatible lev dans les liquides silicates qui
conduit sa concentration la plus leve dans les liquides les plus felsiques et la
prdominance des granites et des rhyolites comme sources dU primaires pour les
gisements duranium. Malgr son comportement incompatible trs marqu, les gisements
dU rsultant directement de processus magmatiques sont relativement rares. Dans la
plupart des gisements lU est mobilis par des fluides hydrothermaux ou des nappes
phratiques bien aprs la mise en place des roches ignes. Parmi les diffrents types de
granites, seuls certains ont des teneurs en U et des proprits physiques et chimiques
permettant la cristallisation de minraux accessoires partir desquels lU sera plus ou moinsfacilement lessivable pour la formation de gisements dU. Les premiers granites sur la terre
qui ont pu cristalliser de luraninite qui sont apparus vers 3.1 Ga, sont les granites fortement
potassiques du craton du Kaapval (Afrique du Sud) qui a reprsent la source de luraninite
dtritique des conglomrats galets de quart du Dominion Reef et du Witwatersrand. Quatre
types de roches ignes peuvent tre suffisamment enrichies en U pour reprsenter une
source pour des gisements dU : peralcalines, mtalumineuses calco-alcalines fortement
-
8/13/2019 Felsic Magmatism and U Deposits
6/62
5
potassiques, peralumineuses de type L, et les pegmatodes anatectiques. Les roches ignes
peralumineuses plutoniques de type L dans lesquelles lU est localis de manire dominante
dans luraninite ou dans le verre de leurs quivalents volcaniques reprsente les meilleures
sources dU pour les gisements hydrothermaux ou lis la circulation deaux superficielles.
Les granites ou synites peralcalines sont associes aux seuls gisements dU magmatiques
drivant dune cristallisation fractionne extrme. Le caractre trs rfractaire des minraux
duranium dans ce type de gisements ne permet pas leur exploitation dans les conditions
conomiques actuelles et en font des sources duranium non favorable pour la gense
dautres types de gisements. Par contre les roches volcaniques peralcalines felsiques, dans
lesquelles lU est principalement localis dans la matrice vitreuse, reprsentent une
excellente source pour beaucoup de types de gisements. Les roches plutoniques calco-
alcalines fortement potassiques reprsentent source dU significative seulement lorsque les
minraux accessoires uranifres (U-thorite, allanite, oxydes de Nb) sont devenus
mtamictes. Les volcanites de la mme gochimie peuvent galement tre une source dU
favorable si une large part de lU localis dans la matrice vitreuse. Le plus grand gisement
dU du monde, Olympic Dam en Australie du sud est situ au sein de roches plutoniques et
volcaniques fortement potassiques et trs fractionnes, mais lorigine de la minralisation en
U nest pas encore bien comprise. Les pegmatodes anatectiques avec de luraninite
dissmine, aussi appels alaskites, qui rsultent de la fusion partielle de mtasdiments
et/ou de mtavolcanites felsiques riches en U, renferment de grands gisements dU faible
teneur tels que ceux de Rssing et Husab en Namibie.
Lvaluation de la potentialit des roches ignes reprsenter une source dU efficace dans
une province donne reprsente une tape critique, durant les premiers stades de
lexploration pour la plupart des gisements dU. En particulier une utilisation plus
systmatique des inclusions magmatiques afin de caractriser la gochimie des magmas
sources et de leur teneur en U est dun intrt majeur pour valuer le potentiel source des
bassins sdimentaires prsentant une contribution volcanique sous forme de tufs felsiques.
-
8/13/2019 Felsic Magmatism and U Deposits
7/62
6
INTRODUCTION
Uranium in silicate magmas exhibits a strongly incompatible behavior because of its large
ionic radius and high valence which prevents its incorporation into the structure of the main
rock forming silicates. As a result, during partial melting and crystal fractionation, U is
preferentially fractionated into silicate melts. Such a behavior has several major
geochemical, geophysical and metallogenic consequences: [i] through geological time U has
been continuously transferred from the mantle to the Earth crust, and within the continental
crust towards its upper part together with other incompatible elements and more particularly
Th and K, [ii] consequently radiogenic heat production is maximized in the upper crust, and
thus radiogenic heat flux production distribution may be used to delineate radioelement
enriched crustal blocks, [iii] the most felsic melts tend to be the most enriched in U, and [iv]
granites and rhyolites represent the primary sources of uranium for the formation of U
deposits. However, despite, the strongly incompatible behavior of U, deposits dominantly
resulting from magmatic processes are rare. In an average granitoid, with a U enrichment of
3 to 4 ppm, uranium is dominantly held within the crystal structure of accessory minerals
[zircon, apatite, monazite, titanite, xenotime ], from which U cannot be leached by most
geological fluids. Typical range of uranium concentrations measured in rock forming minerals
and accessory minerals are given in the Figure 1. Only some specific granites have higher U
contents permitting the crystallization of other types of accessory minerals from which U can
be more or less easily leached for the formation of U deposits. On this basis Moreau [1966]
was the first to define the notion of fertile granites, which has been very fruitful for uranium
exploration.
The aim of the present paper is review the main types of igneous rocks that are sufficiently
enriched in U to be of metallogenic interest, to define the processes leading to their genesis
through time, this will facilitate an evaluation of the rock suites best suited to U sources, as
-
8/13/2019 Felsic Magmatism and U Deposits
8/62
7
well as the specific conditions under which U deposits can be formed by magmatic,
hydrothermal or surficial processes from these sources.
THE DIFFERENT TYPE OF URANIUM-RICH IGNEOUS ROCKS
Propos ed classi f icat ion
The three main types of igneous rocks which can be enriched in U above their Clarke values,
will be distinguished according to in the A/CNK versus A/NK plot of Shand [1943]. They are
the peralkaline, metaluminous, and peraluminous felsic igneous rocks [Fig. 2]. The use of an
aluminum saturation index is particularly relevant for understanding the behavior of uranium
and associated incompatible elements such as Th, Zr, REE in magmatic rocks because
the fractionation of these elements is controlled by the solubilities of the accessory minerals
such as monazite, zircon, uraninite, which are in turn dependant on the degree of aluminum
saturation of the silicate melt [Peiffert et al., 1994; 1996; Montel et al., 1993; Watson &
Harrison 1983, ], as well as other parameters such as temperature and volatile element
content. The A-B diagram of Debon & Lefort [1988] will be also used to further refine the
distinction between the different types of igneous rocks, and to track the evolution of the
aluminum saturation index during magmatic fractionation. Each of these rock types is
characterized by a specific magmatic fractionation of Th and U and a specific accessory
mineral paragenesis [Cuney & Friedrich 1987]. The distribution of U between the different
uranium hosting accessory minerals is of critical importance for the genesis of U
mineralization associated with these rocks. This aspect will be discussed in more detail
below. A fourth type of igneous rock which can be enriched in uranium corresponds to
weakly peraluminous to metaluminous granitoid rocks occurring in migmatitic domains They
are generally referred to as alaskite or anatectic pegmatoid.
Peralkal ine igneous rocks
-
8/13/2019 Felsic Magmatism and U Deposits
9/62
8
These rocks are characterized by an excess of alkalies, either sodium or potassium, with
respect to the amount aluminum bound to the feldspars [Fig. 2] and they are generally
enriched to variable degrees in high field strength elements and especially in uranium. They
can be quartz saturated [peralkaline granites or rhyolites] or undersaturated [syenites or
trachytes]. They are equivalent to the A1-type granite of Eby [1992]. Many hypotheses have
been proposed for the genesis of peralkaline rocks [e.g., Macdonald, 1987]. In the present
paper we will consider that peralkaline magmas derive from low degrees of partial melting of
the mantle, which may itself have been previously enriched in incompatible elements, to
produce alkali basalts, and followed by protracted magmatic fractionation to generate the
most felsic magmas. This model provides an explanation for the fact that peralkaline igneous
rocks are always enriched in U and other incompatible elements. The main parameters
controlling their degrees of enrichment are: [i] the degree of partial melting of the mantle, i.e.
the lower the melting rate will, the richer in uranium will be the silicate melt, [ii] the degree of
enrichment of the mantle by fluids derived from the subducted slab and sediments, [iii] the
degree of fractionation of the magma after its extraction, and [iv] the importance of uranium
fractionation in exsolved magmatic fluids.
Metalumin ous hig h-K calc-alkaline igneous rocks
Certain of the metaluminous calc-alkaline igneous rock family [I- and A2-type in the
alphabetical classification] are enriched in potassium and other incompatible elements [Fig.
2]. Such igneous rocks are called high-K calc-alkaline granite [A2-type granite of Eby 1992]
or shoshonitic granite when K-enrichment reaches levels above 5-6 wt%. These rocks are
metaluminous because of an excess of calcium not balanced by aluminium as in the
plagioclase structure. This calcium is hosted by Ca-rich minerals devoid of, or poor in
alumina, such as clinopyroxene, amphibole, titanite and allanite. Several hypotheses have
been proposed for the genesis of these rocks: partial melting of K-rich meta-andesites
[Roberts and Clemens, 1993], mixing of basaltic with felsic magmas derived from
metasediments [Davis & Hawkesworth, 1993], assimilation of metapelites by high-Al basaltic
-
8/13/2019 Felsic Magmatism and U Deposits
10/62
9
magmas [Patio Douce, 1995], and melting of metasomatized mantle, eventually
accompanied by assimilation of crustal rocks, associated with fractional crystallisation [e.g.,
Schaltegger & Corfu, 1992]. But, at least for the basic to intermediate highly potassic
magmas metasomatism of the mantle by subduction fluids would appear to be the main
process for explaining their enrichment in K, U, Th.
Peraluminous igneous roc ks
All igneous rock with an A/CNK index greater than 1.1 have been defined as S-type by White
& Chappell [1977], because of their presumed derivation from the melting of
metasedimentary rocks. However, in the A-B plot of Debon & Lefort [1988] [Fig. 3] several
types of contrasting fractionation trends can be differentiated within the peraluminous field
composition.
S-type granites, have been first defined in the biotite-cordierite- bearing Kosciusko batholith
[southeastern Australia] by White & Chappell [1977]. In the A-B diagram [Fig. 3] they define a
trend in which the most mafic compositions plot in the center of the greywacke field with the
highest peraluminous indices. Such compositions result from a high degree of partial melting
[> 50 %] of metagreywacke or metapelite in dry conditions at temperatures of 800C to
1000C [Burkhard, 1991; Vielzeuf & Holloway 1988]. During magmatic fractionation, with
decreasing B value, the aluminous saturation index A typically decreases as a result of
unmixing of femic and peraluminous restitic minerals [cordierite and or garnet] in accordance
with the model proposed by White and Chappell [1977]. The composition of the magma
evolves towards the eutectic [the origin of the AB diagram] with a positive correlation
between the A and B parameters.
Guret-type granites [G-type], as defined in the French Massif Central, [Stussi & Cuney,
1993; Turpin et al., 1989] have the same range of mafic mineral proportions as the S-type
Kosciusko Batholith, but the correlation between the A and B parameters is negative,
implying a different genetic processes. The least fractionated granites, richest in mafic
-
8/13/2019 Felsic Magmatism and U Deposits
11/62
10
minerals [mainly biotite], are the least peraluminous. The most leucocratic bodies are the
most peraluminous, with increasing cordierite muscovite proportions. RbSr and SmNd
isotopic studies [Turpin et al.1989] have shown that this type of geochemical trend can be
explained by a mixing between a peraluminous leucocratic granitic melt derived from a
limited amount of partial melting of crustal material and a metaluminous melt derived from
the partial melting of metaluminous rocks at the base of the continental crust or from the
partial melting of the mantle.
Metaluminous calc-alkaline igneous rocks[I & A2 type] may become peraluminous as a
result of one or more of the following processes: [i] extreme magmatic fractionation of
metaluminous minerals like amphibole or pyroxene witch selectively depletes the melt in
calcium but not in aluminium; [ii] assimilation of peraluminous material during ascent of the
magma through the continental crust; [iii] late magmatic to hydrothermal alteration leading to
the fractionation of Na, K, and/or Ca into Cl-bearing late magmatic to hydrothermal fluids.
This may lead to the crystallization of muscovite in the miarolitic cavities of some granite
when fluid oversaturation of the magma occurs at shallow levels, or to the sericitization of thefeldspars during post-magmatic hydrothermal circulation. Generally, this type of
peraluminous igneous rock represents a small volume of the whole calc-alkaline magmatic
complex and its peraluminosity remains limited, except for the most fractionated portions of
the suite, such as the low phosphorus Rare Metal Granites [Linnen & Cuney 2005, ern et
al.2005].
L-type igneous rockscorresponds either to biotite+muscovitegarnetcordierite
leucogranites, as exemplified by the peraluminous leucogranite complexes of Limousin
(French Massif Central) [Cuney et al., 1989] or the felsic sillimanite+muscoviteandalusite
volcanic rocks of Macusani in Peru [Pichavant et al., 1988]. Contrary to the typical S-type
granites, mafic mineral contents remain below 10%, and the peraluminous index increases
markedly during magmatic fractionation [Fig. 3]. L-type igneous rocks forms from low degree
-
8/13/2019 Felsic Magmatism and U Deposits
12/62
11
of partial melting (
-
8/13/2019 Felsic Magmatism and U Deposits
13/62
12
content of these early felsic rocks is typically below 1 to 2 ppm. At such low concentration, U
is nearly entirely hosted by the structure of common accessory minerals [zircon, titanite,
monazite, allanite, apatite] and thus cannot have been significantly extracted by
hydrothermal fluids. Uraninite or other U-minerals have never been reported in pre-
Mesoarchean magmatic rocks. Even if a small fraction of U could have been extracted from
the accessories, the reduced atmospheric conditions during this period of time would not
have permitted the oxidation of U from the tetravalent state, its form within the accessory
minerals, to the hexavalent state required to form the highly soluble uranyl complexes.
Hence, before 3.1 Ga, U was never sufficiently enriched to represent a viable source for the
formation of ore deposits. Thorium, which has the same ionic radius as U, and which exists
only in the tetravalent state in natural systems, behaved at that time similarly to U in reducing
conditions, and the initial Th/U ratio of the primitive Earth of about 4 has remained nearly
constant under these conditions.
The first uranini te bearing granites
Between 3.1 and 2.2 Ga U continued to be dominantly fractionated by magmatic processes
but new conditions of fractionation permitted the appearance of the first granites sufficiently
enriched in U to crystallize uraninite. The oldest of these granites are known at 3.1 Ga in the
Kaapvaal-Kalahari craton in South Africa [Robb & Meyer, 1988; 1990]. They are highly felsic
and much richer in potassium than the TTG. They belong to the Granodiorite- Granite-
Monzogranite suites [GGM] of de Wit [1998]. They were intruded between ~3.2 and 3.0 Ga
inside and along the boundaries of a series of crustal blocks which collided to form the
Kaapvaal craton [de Wit et al., 1992]. Then, between ~2.75 and 2.5 Ga, at least three other
generations of potassic granite were emplaced in this region [Poujol et al., 2003]. Aplites and
pegmatites enriched in uraninite, associated with large high-K metaluminous to slightly per-
aluminous granitic complexes [Clemens et al., 2010] also dated at about 3.1 Ga, have been
identified in the Barbeton belt [Carrou et al., 2012]. High-K metaluminous granites are also
known in most other Archean cratons, as in the Early Archean Pilbara, the Late Archean
-
8/13/2019 Felsic Magmatism and U Deposits
14/62
13
Yilgarn cratons, and the basement of the East Alligator River Uranium district of Australia, in
the Manitoba, Superior province and Central Qubec in Canada, Wyoming in the USA, in the
Amazon craton of Brazil, in the Dharwar and Singhbum cratons of India, the Zimbabwean
craton and others [Table 1]. Generally, these granites cover much larger surfaces than the
TTG in present exposures [Bowring and Housh, 1995; Kinny & Nutman, 1996; Frost et al.,
1998; Drppel et al., 2009]. For example, in the Wyoming province, TTG are restricted to
rocks older than 2.8 Ga, whereas Late Archean highly potassic granites represent most of
the plutonic rocks, and were emplaced during four periods, at ~2.8, 2.67, 2.63, and 2.55 Ga
[Frost et al., 1998]. In the Archean basement of the Rum Jungle province TTGs are nearly
absent. Despite the high U contents and low Th/U ratios of these potassic granites, uraninite
has been relatively rarely identified in petrographic descriptions and still more rarely
analyzed. Also, the aplites and pegmatites, deriving from the extreme fractionation of these
granites were probably the richest in uranium, as observed in the occurrences of the
Barbeton Belt [Carrou et al., 2012]. However, these aplites and pegmatites have been
probably largely eroded, because they were generally emplaced in their apices.
Some Archean uraninites may derive from magmatic hydrothermal processes related to the
unmixing of a fluid phase from highly fractionated high-K calc-alkaline magmas, such as
those of the iron oxide-copper-gold [U] deposits of the Amazonian craton in Carajas, Brazil
[Tallarico et al., 2005]. For example, the Igarap deposit is spatially and probably genetically
related to the high-K calc-alkaline granites of Old Salobo [2573 2 Ma; Requia et al., 2003]
and Itacainas [2560 37 Ma, Souza et al., 1996].
Genetic models for the Arch ean high-K granites
Several hypotheses have been suggested to explain the genesis of Archean potassic
granites. One suggestion is that they originated through partial melting of the TTGs and
associated metasedimentary rocks at medium to deep crustal levels [Frost et al., 1998]. It
has been also suggested that they were derived from the partial melting of a mantle wedge
-
8/13/2019 Felsic Magmatism and U Deposits
15/62
14
peridotite previously metasomatized either by melts derived from slab melting [Martin et al.,
2010] or by fluids enriched in incompatible elements produced by the dehydration of
sediments injected along the subduction zone, as proposed for post-Archean high-K
granites.
Partial melting of early Archean crust does not explain the high U contents of high-K granites
and in particular those which are able to crystallize uraninite. Very small increments of partial
melting of TTG and/or associated sediments (typically containing less than 1 ppm U) would
be required to generate granites enriched in U by 1 to 2 orders of magnitude. Another option
would to consider the partial melting of a mantle wedge peridotite metasomatized through
interaction with slab melts as proposed to explain the origin of the sanukitoids [Martin et al.,
2010]. However, these rocks are metaluminous monzodiorites to granodiorites rich in Mg, Ni,
Cr, in most LILE and in LREE, and have U contents that are too low to permit the
crystallization of uraninite. A similar mechanism followed by mixing with crustal melt is
proposed for the Late Archean Closepet metaluminous porphyritic monzogranite which is
richer in incompatible elements [Moyen et al., 2001]. The latter characteristic is explained bya higher enrichment of the mantle source by slab melts [Jayananda et al., 2000]. However,
the highest enrichment of radio-elements in the Closepet granitic complex is reached in its
northernmost part with 4.5 wt% K2O, 40 ppm Th, and 6 to 7 ppm U [Kummar & Ready, 2004].
Such high Th and U contents and Th/U ratios is explained by the occurrence of allanite as
the main U and Th bearing mineral [Jayananda et al., 2000], but not of uraninite which
requires lower Th/U ratios to crystallize.
Hence, the genesis of uraninite bearing high-K magmas probably requires a greater initial
enrichment of U and Th in the subcontinental lithospheric mantle. These elements are
particularly mobile through a fluid phase and may derive from the dehydration of subducted
sediments rather than from the subducted oceanic slab in which water in bound to more
refractory minerals such as amphibole. During the Mesoarchean, therefore, subduction of
sediment may have occurred locally to produce significant U and K enrichments in the
-
8/13/2019 Felsic Magmatism and U Deposits
16/62
15
subcontinental lithosphere. The partial melting of the metasomatized mantle wedge could
have generated K- and U-enriched andesitic magmas with subsequent fractionation giving
rise to granitoid intrusions enriched in incompatible elements as proposed for the modern
high-K calc-alkaline granites. However, further research is required to constrain the
mechanisms of U enrichment in the early high-K granites able to crystallize uraninite from
about 3.1 Ga.
The first peraluminou s uranini te bearing igneous ro cks
The first felsic magmas to crystallized a low Th-uraninite began to appear by about 2.7 Ga
such as the Tanco pegmatite in Manitoba, Canada [Duhamel et al., 2009]. These granites
are enriched in uranium to 10 - 100 ppm [Table 1], but the most felsic members are typically
depleted in most other HFSE elements [Th, REE, Zr] because of the low solubility of Th-
REE-Zrbearing accessory minerals in low-temperature highly peraluminous melts [Montel,
1993; Watson & Harrison, 1983; Cuney & Friedrich, 1987].
The first peralkal ine igneous rocks
Although peralkaline rocks are commonly observed in Archaean terranes, they are
volumetrically insignificant, and represented by lamprophyric dikes and syenitic intrusions.
The oldest well-documented examples are the 2.7 Ga high-K trachyte and leucite phonolite
from Kirkland Lake in Canada [Blichert-Topf et al., 1996]. Their the volumetric insignificance
during early Archean times may result from the fact that mantle temperatures were too high
to obtain the low degree of partial melting needed to generate this type of magma [Hattori et
al., 1996]. It might also be that they were poorly preserved, because they emplaced at a very
high structural level [Blichert-Toft et al., 1996]. Their degree of U-enrichment in these rocks
was also moderate.
Relative uranium fertility of uranium-rich igneous rocks
-
8/13/2019 Felsic Magmatism and U Deposits
17/62
16
Despite their U -enrichment relative to the Clarke value, the igneous rocks described above
have not all the same potential to represent an efficient source of U for the genesis of U
deposits. Beside their degree of U-enrichment, their fertility depends on the nature of the
sites in which U is hosted and the ease with which U can be leached by hydrothermal or
fluids of ground water. The following section examines the nature of the different U bearing
mineral parageneses in various igneous rock types.
Peralkal ine igneous rock s
In peralkaline rocks the excess of alkalies with respect to alumina [Na+K/Al > 1] and the high
temperature of the silicate melts, favor both a strong melt depolymerization and consequently
a high solubility of the large highly charged elements, such as U, Th, Zr, Nb, Ta and the
REEs [Peiffert et al., 1994, 1996, Montel, 1993; Watson & Harrison, 1983]. Hence, uranium
is continuously enriched with the other incompatible elements during magma fractionation,
which all reach the highest concentrations in the most fractionated peralkaline melts.
Typically, in a Th [Zr, REE] versus U diagram, peralkaline complexes define a positive
correlation [Fig. 4] and their Th/U ratios remain close to the average crustal ratio during
magmatic fractionation. Interaction with late-magmatic fluids may lead to a slight decrease of
the Th/U ratio.
During crystallization of highly fractionated peralkaline melts [Fig. 5], in plutonic bodies,
abundant and complex Zr, REE, Th, Nb, and Ta minerals form (e.g.: pyrochlore
(Ca,U,REE)(Nb,Ta,Ti)2O
6(O,OH,F), eudyalite
(Na,LREE,Ca,K)15(Ca,Mn)6(Mn,Fe)3(Zr,Nb,Hf)3(Nb,Ta,Si)Si26O74 (OH,Cl,F)2,2H2O,
steenstrupine Na14Ce6Mn2Fe2(Zr,Th,U)(Si6O18)2(PO4)7,3H2O), with U as a minor element
substituted in the structure of all these minerals [Cuney & Friedrich, 1987]. Individual
crystals of uraninite are generally not able to crystallize despite the strong enrichment in
uranium of these melts. Extreme fractional crystallization of peralkaline melts may lead to U,
Th, Zr, and REE concentrations in the silicate melts up to several hundreds to thousands of
-
8/13/2019 Felsic Magmatism and U Deposits
18/62
17
ppm and more rarely up to several weight percent. However as uranium is hosted in
accessory minerals from which it cannot be leached by hydrothermal fluids or ground waters,
they do not represent a favourable source of uranium. However, highly fractionated
peralkaline rocks may become significant U sources when U is hosted by silicate minerals
and when the latter become metamict.
By contrast with peralkaline plutonic rocks, peralkaline felsic volcanic rocks [e.g., liparites]
represent an excellent U source, because most of the U is in the glassy matrix. When the
glass becomes devitrified during alteration, U can easily be mobilized. These units form
extensive and thick layers of pyroclastic tuffs [ignimbrites] within and outside volcanic
calderas. The Latium Province in Italy, an area covering more than 2000 km 2, represents one
of the most recent example of such a pyroclastic tuff sheet strongly enriched in U [Villemant
& Palacin 1987].
High-K calc-alkal ine igneous rock s
The intermediate to high temperatures of highly fractionated high-K calc-alkaline melts and
their metaluminous to slightly peraluminous compositions lead to a variable and intermediate
degree of polymerization of the silicate melts. Consequently, the solubility of Th, Zr, and REE
bearing accessory minerals will be variable and lower than in peralklaine melts, and the
beahviour of Th, Zr and REE relatively to uranium will likewise vary, with lower degrees of
enrichment [Fig. 4]. With magmatic fractionation and increasing U concentrations, these
elements may increase slightly in the magmas, remain constant, or decrease slightly,
depending on the melt temperature and aluminosity. These magmas are also characterized
by high Ca contents. When the CaO contents in the silicate melt exceeds about 1 wt.%,
crystallization of Ca-rich minerals such as amphibole, titanite and allanite occur. These
minerals incorporate REEs as well as minor quantities of Th and U, that substitute easily for
Ca together with in their structure [Fig. 5]. If the Th/REE ratio of the melt is sufficiently high,
Th and U will crystallize together as thorite [Th-silicate], which may incorporate up to 30 wt.%
-
8/13/2019 Felsic Magmatism and U Deposits
19/62
18
UO2 in its structure [Pagel, 1982; Cuney & Friedrich, 1987]. Consequently, in a melt with a
Th/U ratio close to 4, most of the uranium will be incorporated in the structure of uranothorite.
This mineral, being very refractory, will not be affected by hydrothermal fluids or ground
waters which circulate soon after the granite emplacement and will not represent a source for
uranium deposits [Cuney & Friedrich 1987]. However, uranothorite and other Th- and U-rich
silicate phases [allanite, zircon] may become efficient U sources during later fluid circulation
events when their structure is destroyed as a result of alpha-recoil during U decay
[metamictisation] [Pagel, 1982]. Significant metamictisation of the U-bearing silicates typically
requires a time laps of 200 Ma.
Allanite may represent the main U bearing host for high REE/Th ratios in the melts, whereas
Nb and Nb-Ti oxides become the main U bearing mineral for high Nb/Th ratios. When the
fractionated high-K calc-alkaline melts become slightly peraluminous and/or when their
temperature and Ca-content has decreased sufficiently, monazite may become stable and
Th-bearing accessory minerals start to fractionate to induce a decrease in Th/U ratios, and
permit the crystallization of uraninite. However, the proportion of uraninite is generally smalland such highly fractionated granites generally represent only small volumes of high-K calc-
alkaline complexes. So, the amounts of U available as uraninite remains limited. Moreover,
when uraninite crystallizes in equilibrium with Th-rich minerals [uranothorite], it is
characterized by high Th contents [8 to 15 wt.% ThO2] [Pagel, 1982] which make it less
soluble in hydrothermal or surficial fluids.
In conclusion, U-rich high-K calc-alkaline intrusions bodies may become a significant U
source for the formation of U deposits, when their U-bearing accessory minerals have
become metamict or when they contain a significant proportion of uraninite. However, high
uraninite contents in such granite suites are rare compared to peraluminous leucogranites,
and associated secondary U deposits will be limited in extent.
-
8/13/2019 Felsic Magmatism and U Deposits
20/62
19
High-K calc-alkaline volcanic rocks may represent a significant uranium source if the
magmas are fractionated and if the U is dominantly hosted by the glassy matrix rather than in
U-bearing accessory minerals.
Peraluminous igneous roc ks
In S-type igneous rocks, the high degrees of melting of source lithologies does not permit
any selective partial melting of specific protolith[s] enriched in uranium above the crustal
Clarke value. Hence, the U concentrations of the various lithological layers are averaged and
the U content of the melt remains moderate with U dominantly bound to the structure of the
common accessory minerals. During magma fractionation, decreasing temperature during
restite unmixing leads to the fractionation of the U-bearing accessory minerals.
Consequently, the enrichment in U in the residual melts remains moderate, to a level never
sufficient to obtain the crystallization of a significant proportion of U as uraninite. This type of
granite is not known to be associated with U deposits.
In G-type igneous rocks, even if the crustal protolith undergoing partial melting was enriched
in U, the U content of this melt will decrease because of its mixing with a metaluminous melt
poor in U. Such granite is also not known to be associated with U deposits.
L-type igneous rocks,when enriched in U, represent highly favorable U sources because U
is dominantly hosted in Th-poor uraninite, easily leachable by hydrothermal fluids or ground
waters. Crystallization of U - dominantly as uraninite - results from a succession of
processes:
[i] The protoliths submitted to melting have to be enriched in U significantly above the Clarke
value for the upper continental crust [> 2.7 ppm], in order to have a large proportion of U
hosted outside the structure of the accessory minerals. The fraction of uranium hosted in
accessory minerals, such as monazite, zircon, and apatite, cannot contribute to the
enrichment of the melts because accessory minerals are only sparingly soluble in low
temperature peraluminous silicate melts [Watson & Harrison 1983, Montel 1993]. These
-
8/13/2019 Felsic Magmatism and U Deposits
21/62
20
accessory minerals will be enriched in the restite material together with U [Friedrich et al.,
1987].
[ii] The degree of partial melting has to remain low to favor U enrichment in the resulting melt
and to melt preferentially the lithologies dominantly composed of quartz and feldspar [meta-
arkoses, felsic volcanic or plutonic rocks] which are the ones the most likely enriched in U.
[iii] During fractional crystallization of the U-enriched peraluminous melts, decreasing
temperature and increasing peraluminosity decrease accessory minerals solubility along a
protracted liquid-line-of-descent. More particularly, the fractionation of monazite, the main
Th- and REE-bearing mineral in peraluminous magmas, depletes melt in Th and REE.
Uranium is not depleted because monazite and other accessory minerals [zircon, apatite]
incorporate only minor amounts of uranium [Fig. 5]. As a consequence, the U remaining in
the melt, not retained in the structure of the accessory minerals, continues to be enriched
during fractionation until the silicate melt reaches uraninite saturation and Th-poor uraninite
crystallizes [Cuney & Friedrich 1987]. It is remarkable that the U-rich peraluminous granites
associated with uranium deposits, have U concentrations in the order of 10-30 ppm,
consistant with values obtained in the experimental studies of uraninite solubility in
peraluminous silicate melts at about 800C [Peiffert et al., 1994; 1996].
U dominantly hosted by Th-poor uraninite, represents a very easily leachable source of metal
[Cuney & Friedrich 1987]. The most fractionated members of this type of peraluminous
granite are represented by rare metal, high-P highly peraluminous granite or pegmatite [LCT-
type], extremely depleted in Th [down to less 1 ppm], Zr [~20 ppm], and REE [close to or
below chondritic abundances] [Linnen & Cuney 2005, ern et al.2005]. In a Th [Zr, REE]
versus U diagram, these elements are reversely correlated [Fig. 4]. Hence, the Th/U ratio of
such granite decreases during fractionation. Magmatic fractionation of highly peraluminous,
low-temperature melts is probably the only way to produce differential fractionation of thorium
relative to uranium without requiring a redox process.
-
8/13/2019 Felsic Magmatism and U Deposits
22/62
-
8/13/2019 Felsic Magmatism and U Deposits
23/62
22
peralkaline complexes. These intrusions are generally located in the apical part of the
complexes or at their margins, where low viscosity residual melts and associated exsolved
fluids are emplaced. The fluid/melt partition coefficients are extremely low in peralkaline
systems [Peiffert et al., 1996]. However in some occurrences, U, Th, and the REE are
transported by hydrothermal fluids a few hundreds of metres [e.g., Bokan Mountain] to
several kilometres [e.g. Th veins of the Front Range] from the intrusion, but none of these
veins has sufficient uranium grade or tonnage to be mined.
These deposits may represent very large, low-grade U and Th resources, such as the
Kvanefjeld deposit at Ilmaussaq, Greenland [Srensen 2001, Bohse et al.1974]. Other
major occurrences of this type are: Pocos de Caldas, Brazil [Fraenkel et al.1985], Bokan
Mountain, Alaska [MacKevett 1963], Lovozero Massif, Kola Peninsula, Russia [Balashov
1968], and the Kaffo Valley, Nigeria [Bowden & Turner 1974]. Such an association can also
be extended to the ultimate fractionation products of peralkaline complexes, namely
carbonatite intrusions such as Palabora, South Africa [Verwoerd 1986]. However, even if the
U content of some deposits of this type may be relatively high, they generally not have beenmined because of the high cost of uranium extraction from refractory minerals.
The Kvanefjeld deposit in the Ilmaussaq peralkaline complex [Srensen et al.1974]
represents one of the best examples of of a U deposit associated with the most strongly
fractionated syenite of a peralkaline complex, where U is mainly hosted by steenstrupine, a
complex silico-phosphate of U, Th, and REE. The resources of the deposit are over 250,000
tU at a grade around 200 ppm.
Low degrees of partial meltingof uranium-rich metasediments or felsic meta-igneous rocks
leads to the formation of anatectic pegmatoids with disseminated uraninite associated with
highly variable amounts of other U-bearing accessory minerals. The type example is the
Rssing deposit in Namibia whose mineralization is hosted by granitic pegmatite sheets and
small plutonic bodies, called alaskites [Berning et al., 1976; Cuney 1980; 1982; Cuney &
-
8/13/2019 Felsic Magmatism and U Deposits
24/62
23
Kyser, 2008]. They typically intrude into epicontinental sediments, possibly associated with
acidic volcanic rocks, metamorphosed to a high grade with accompagning anatexis. The
Rssing U deposit in Namibia [246,500 t] is one of the lowest grade [300 ppm] U deposits
ever mined.
The large accumulation of alaskite dykes with relatively high U grade at Rssing results from
the combination of the following parameters: [i] a U-rich source represented by
intracontinental platform sediments [arkoses, quartzites, black shales, marls, limestones],
probably associated with felsic volcanic rocks; [ii] a low degrees of partial melting, dominantly
affecting the quartz-feldspar-rich lithologies of the volcanosedimentary sequence which
explains their weakly peraluminous character and high degree of U enrichment; [iii] a
structural control of alaskite emplacement linked to the late kinematic evolution of the
Rssing Dome [Basson & Greenway, 2004]; [iv] the existence of a chemical barrier, which
was able to stop the rise of the alaskitic melts which reacted with enclosing marbles of the
Rssing Formation or calcsilicate rocks of the Khan Formation to form skarns. This in turn
led to the production of CO2shifting the solidus of the melts to high temperatures to facilitatetheir accumulation in the vicinity of the marble layers; [v] a reducing barrier represented by
the sulfide- and graphite-bearing Rssing Formation, which has prevented the fractionation
of U in magmatic fluids at this level, and promoted the entrapment of U from magmatic fluids
deriving from alaskites crystallized at deeper structural levels under oxidized conditions; and
[vi] favorable climatic conditions which allowed the oxidation of uraninite in the weathering
zone and precipitation of uranophane in fractures enriching the upper part of the deposit.
Many other occurrences of uraninite-rich pegmatoids are known worldwide but all deposits
which are being mined or which will be mined in a near future [e.g., Usab] are located in
Namibia, except for the much smaller deposits of the Bancroft district in Canada which have
been mined in the seventies and eighties.
Hydroth ermal deposits
-
8/13/2019 Felsic Magmatism and U Deposits
25/62
24
For many hydrothermal deposits, the source of U is represented by plutonic rocks, either L-
type peraluminous leucogranite or high-K calc-alkaline granites or equivalent volcanic rocks.
Peralkaline plutonic rocks do not represent a significant U source, but peralkaline volcanic
rocks and especially peralkaline tuffs are the major U source for a variety of deposits.
Hydrothermal granitic U depositsderive their uranium mostly from L-type peraluminous
leucogranites [Cuney, 1978; Friedrich et al., 1987]. The largest province of this type is the
mid-European Variscan Belt with uranium deposits associated with Carboniferous granite
plutons which extends for over 2,000 km from Morocco to the Erzgebirge. Similar uranium
provinces are known in southeastern China with the Jurassic to Cretaceous granite plutons
of the Yanshanian belt and in Argentinian with the Achala Batholith of Devonian age.
In the French part of the Variscan orogen, peraluminous two-mica leucogranite emplaced
between 335 and 310 Ma. They are derived entirely from the partial melting of the continental
crust [Bernard- Griffiths et al.1985] during the collision between the Eurasian and African
continental plates at about 400 Ma. The fertile granites in which U is dominantly hosted in
uraninite are those emplaced along a High Heat Flow and Heat Producing (HHFHP) belt
spreading from Northern Brittany to the Limousin area. The (HHFHP) belt corresponds to a
15 km thick crustal block enriched in U, Th and K during the Neoproterozoic to lower
Paleozoic [Vigneresse et al., 1989]. Leucogranites located outside of the HHFHP belt have
low U content and are not associated with U deposits. Therefore, the genesis of the fertile
leucogranites clearly requires the partial melting of a U enriched source. The Sr and Nd
isotopic studies of Turpin et al.[1990] have shown that Late Proterozoic to Early Paleozoic
felsic orthogneisses represent a possible source lithology for the Saint Sylvestre
leucogranite. More particularly, the potassic calc-alkaline orthogneiss of La Dronne from
central Limousin, with an average of 6.9 ppm U represents a likely protolith [Bourguignon
1988].
-
8/13/2019 Felsic Magmatism and U Deposits
26/62
25
The U deposits of the French Variscides are dominantly located within the granites, or in their
enclosing metamorphic rocks, in the Erzgebirge district. They occur as veins or as
disseminations in de-quartzified granite [episyenite] [Leroy 1978; Cathelineau, 1986].They
are predominantly of Permian in age. The deposition of U in veins is related to low
temperature hydrothermal fluid circulation which largely postdates the emplacement of the
granites by 30 to 40 m.y. [Leroy & Holliger 1984; Cathelineau et al., 1989]. Despite this large
gap, the localization of the U deposits is strongly controlled by the magmatic structures
which were active during the emplacement of fine grained U-rich granite intrusions which
were reactivated as brittle structures to channel hydrothermal fluids [Cuney et al., 1989;
Cuney, 1990]. The importance of U leaching from peraluminous leucogranites by
hydrothermal fluid for the formation of U deposits has been recently emphasized by an
oxygen and 40Ar/39Ar isotopic study on the Questembert granite [Tartse et al., 2013].
High-K calc-alkaline granites may also represent a major source of uranium for hydrothermal
deposits. At Hotagen, in Sweden, U-deposits occur within a Paleoproterozoic high-K calc-
alkaline granite but where uranium was subsequently precipitated during a Caledoniantectonic-hydrothermal event. The large time difference between granite emplacement and
hydrothermal circulations resulted in metamictization of uranothorite, the main U-bearing
mineral, which becomes an easily leacheable source of uranium. Another type of relation
between the granites and the uranium source is provided by the Bois Noirs-Limouzat deposit
in France [Cuney, 1978], with 6,920 t U at grades of 0.27% U. The deposit is hosted within
the Bois Noirs high-K calc-alkaline granite, but drill holes below the deposit have intersected
uraninite-rich peraluminous leucogranites which probably represent the major uranium
source for the deposit [Poty et al.1986]. The Olympic Dam deposit in Southern Australia
represents an even more complex relation between the host high-K calc-alkaline granite and
later fluids, and is discussed further below.
Hydrothermal volcanic uranium deposits are mostly related to peralkaline volcanic rocks. The
world largest uranium district of this type [280,000 t U at 0.2 %] is the late Jurassic
-
8/13/2019 Felsic Magmatism and U Deposits
27/62
26
Stretsovkoye caldera in Transbaikalia, Russia. Hydrothermal circulations occurred during the
wanning stages of magmatic activity within a large caldera. The exceptional size of the
resources in the Streltsovkoye district results from the juxtaposition of four main U sources:
[i] liparitic tuffs which represent 30 to 35 vol% of the volcanic pile, [ii] Variscan U-rich high-K
calc-alkaline granitoids in the basement, [Chabiron et al., 2003], [iii] Ordovician U
mineralization in the basement [Chernyshev & Golubev, 1996], and [iv] fluids expelled from
the volcanic melts or from underlying magma chamber. The latter parameter has a limited
effect, however, because the U fluid/peralkaline melt partition coefficient is strongly in favour
of the melt [KDU fluid/melt = 3.102 to 4.102, Peiffert et al.,1996]. A quantitative estimate of
the amount of uranium which has been liberated by the liparites has been obtained from
mass balance calculations between the uranium content of the melts inclusions from quartz
trapped in the liparites and the average present U content of these volcanic rocks Chabiron
et al., 2003].
High-K calc-alkaline metaluminous volcanic rocks are generally a less favorable U source
because a significant but variable portion of the U in these rocks tends to be trapped inaccessory minerals [Leroy & George-Aniel, 1992]. Most deposits related to this type of
volcanism have a relatively small size.
Highly peraluminous acidic volcanics, mineralized in U are essentially known in the Macusani
district, Peru. Pitchblende and autunite occur in sub-vertical to sub-horizontal fractures in the
top tens of meters of Pliocene crystal-rich flows / tuffs. A resource of 30,000 tU has been
estimated for the whole Macusani district at an average grade of 0.1 % U [IAEA, 2009].
Hydrothermal diagenetic U depositsof tabular or tectonolithologic type may derive a large
part of their uranium from volcanic tuffs, commonly of peralkaline origin, deposited within
continental siliciclastic units of large sedimentary basins and leached by saline diagenetic
fluids. In the Arlit uranium district in Niger, the evidence of an important contribution by
volcanic tuffs in the sandstone of the Tim Mersoi Basin is provided by the presence of
-
8/13/2019 Felsic Magmatism and U Deposits
28/62
27
volcanic shards in the sandstone, of magmatic inclusions in the detrital quartz of volcanic
origin, and of analcimolite levels. The analyses of the magmatic inclusions indicate that a
large part of the volcanic were peralkaline and rich in U [Forbes et al., 1984; Pagel et al.,
2005]. The important uranium contribution from peralkaline volcanic origin in the Tim Mersoi
Basin probably explains the relatively high grade of the Arlit district deposits with more than
100,000 t U at about 0.3 %.
For the Lodve hydrothermal-diagenetic deposit of tectonolithologic type, in France,
Ahmadach et al.[1993] have also determined the parent magma chemistry and initial U
content of the volcanic ash layers which are present through the Lodve basin from the study
of magmatic inclusions in apatite. The volcanic ash layers are presumed to represent of
major U source for the deposit.
Hydrothermal diagenetic U depositswith basement/basin redox control, which are generally
called unconformity related deposits, are characterized by large resources [631,000 t U] and
also comprised the highest grade uranium deposits in the world [e.g. 20 % U average grade
in the McArthur River deposit in the Athabasca, Canada]. The source of uranium for these
deposits is debated. In the case of the Athabasca, it is proposed that uranium is derived
either from the sandstone basin [Ruzicka, 1996; Kotzer & Kyser, 1995; Fayek & Kyser, 1997;
Kyser et al., 2000] or from the basement lithologies [Tremblay, 1982]. A special emphasis
has been put on the abundant uranium-rich peraluminous granites and pegmatites of the
basement [Thomas, 1983; Madore et al., 2000; Annesley et Madore 1999; Hecht & Cuney,
2000; Mercadier et al., 2013], which result from the partial melting of uranium enriched
metasedimentary lithologies initially deposited in an epicontinental setting during the
Paleoproterozoic [Cuney, 2010]. Other possible sources include a series of U-rich high-K
calc-alkaline granites mainly emplaced in Taltson Belt, to the west of the Athabasca Basin
[Brouand et al., 2003]. It has been shown that, due to the exceptionally aggressive nature of
the hydrothermal diagenetic fluids, which are highly saline, very acidic, relatively high
temperature and oxidizing [Derome et al., 2005; Richard et al., 2012], a refractory mineral
-
8/13/2019 Felsic Magmatism and U Deposits
29/62
28
like monazite can be totally destroyed and uranium can be liberated both in crystalline
basement rocks and within the sedimentary basin [Hecht & Cuney, 2000; Cuney & Mathieu,
2000; Gaboreau et al.2007].
Hydrothermal metasomatic U deposits associated with Na-metasomatismcorrespond to
regional scale alteration, controlled by deep crustal structures, and typically characterized by
dequartzification, albitization and later Ca- and less commonly K-metasomatism [Cuney et
al., 2012]. The largest resources of this type are located in central Ukraine ( 280,000 t U at
0.08 to 0.13 %). The alteration may affect high-K calc-alkaline granites as at Lagoa Real in
Brazil [100,000 t U at 0.12%] [Turpin et al., 1988], at Novokonstantinovkoe in Ukraine [Cuney
et al., 2012] and at Kurupung in Guyana [Cinelu et al., 2006; Alexandre, 2010], or felsic
metavolcanics of high-K calc-alkaline typology in the Michelin deposit in Labrador [36,800 t U
at 840 ppm], Canada [Gandhi, 1978], and in the U deposits of northern Sweden such as
Pleutajok [4,000 t U at 0.10%] [Adamek & Wilson, 1977].
Hydrothermal metasomatic U deposits associated with skarns. The type example of this
category is the Mary Kathleen U-REE skarn in Australia [8550 t U at 0.11 %]. The skarns
result from interaction between the volatile- and U-Th-rich high-K calcalkaline Burstall
Granite emplaced at 1737 15 Ma, and the enclosing calc-silicates, as well as highly saline
fluids derived from evaporites [Oliver et al., 1999]. An early phase of U and REE enrichment
is presumed to have occurred in the skarns, at or near the present orebody and related in
time to the emplacement of the granite [Maas et al., 1987]. However the main phase of U-
REE mineralization was generated during a second episode dated at 1550 15 Ma by Page
[1983]. This episode has occurred under upper amphibolite facies conditions [600-650C,
3.5-4 kb] with a new phase of highly saline hydrothermal activity producing intense
scapolitisation of the sediments. Small, disseminated grains of uraninite enclosed in allanite
or along veins are exclusively associated with zones of retrogressed garnetdiopside skarns
[McKay & Miezitis, 2001]. The present U-REE mineralization at Mary Kathleen seems to
-
8/13/2019 Felsic Magmatism and U Deposits
30/62
29
result from the recrystallization of an older, granite-related U-REE mineralization in skarns,
that were upgraded during the later metamorphic hydrothermal event.
Olymp ic Dam deposit
The Olympic Dam iron oxide-copper-gold [IOCG-U] deposit is by far the worlds largest
uranium resource [2,200,000 t U at 230 ppm]. Uranium is a co-product of copper and gold.
The deposit occurs in the center of the high-K calc-alkaline Roxby Downs granite emplaced
at 1.59 Ga at a very shallow structural level [Creaser, 1996]. This granite is the most
fractionated intrusion, and thus the most enriched in U and Th, of the much larger Burgoyne
batholith. Uranium in the Roxby Downs granite is dominantly hosted in uranothorite. Gawler
Range volcanic rocks of similar geochemistry were extruded contemporaneously over large
areas. However, the genetic model for the genesis of the uranium mineralization in the
Olympic Dam deposit is still not very well understood. Unlike many other IOCG deposits,
Olympic Dam is entirely hosted within U-rich high K calc-alkaline granites and volcanic. The
most commonly accepted model links the multiple brecciation episodes and the hydrothermal
activity at the origin of the deposit to the emplacement of the Roxby Downs Granite and
extrusion of contemporaneous volcanics [Reynolds, 2000; Johnson & Cross, 1995]. Hitzman
et al.[1992] attribute the genesis of the Olympic Dam ores to a hot, highly saline fluid derived
from a granitic magma which has mixed with an oxidized meteoritic fluid. However, the
source of copper and gold requires other sources and hydrothermal circulation at a larger
scale in the crust [Johnson & McCulloch, 1995].
Observations made by the author on a limited selection of Olympic Dam samples suggest
that uranium minerals comprise minor amounts of euhedral uraninite crystals dispersed
within the mineralized breccia, and a predominant pitchblende phase, either occasionally
altered to coffinite or primary, and U-Ti oxides, occurring mainly in veinlets [Cuney & Kyser,
1998]. The uraninite is interpreted as a early high temperature uranium phase of
mineralization event related to the unmixing of a magmatic fluid derivied from the Roxbydown
-
8/13/2019 Felsic Magmatism and U Deposits
31/62
30
granite. However, its limited abundance may only explain concentrations in the order of some
tens of ppm as commonly observed in many IOCG deposits. The deposition of pitchblende
and coffinite, which represent the major part of the uranium ore minerals, requires the
circulation of oxidized low temperature hydrothermal fluids. For Hitzman & Valenta [2005],
the leaching of U from the wall rocks by such hydrothermal fluids was considered to be the
main source of U in the IOCG deposits, with an enrichment factor in the ore of 10 to 40.
However, at the time of the early magmatic-hydrothermal fluid system, the main uranium
bearing phase in the enclosing Roxbydown was represented by uranothorite generally
considered to be a refractory uranium source in the presence of low temperature
hydrothermal fluids. Hence, the associated hydrothermal fluid circulations have to have
occurred in the order of 200 Ma after granite emplacement, the time necessary for
metamictization of uranothorite and liberation of uranium. A more detailed study of the
uranium mineralization processes is clearly needed for IOCG deposits in general and
especially for Olympic Dam.
Other deposit types
The first uranium deposits of the Earth, the Archean to Early Paleoproterozoic Quartz Pebble
Conglomerates [QPC] of the Dominion Reef and the Witwatersrand Basin in South Africa
and the Elliot Lake district in Canada, derive their uraninite crystals, accumulated by placer
mechanics alongside with other heavy minerals, from highly fractionated Archean high-K
calc-alkaline granites and pegmatites described above. A controversy exist about the granitic
versus hydrothermal orgin of the uraninite from these deposits, but the REE patterns recently
obtained by in situ analysis on uraninite crystals clearly indicate their derivation from a
granitic source [Cuney, 2010; Delpin et al., 2013].
Many other types of U deposits may derive their U from spatially related U-rich granites or
volcanic rocks. Such an origin is proposed for many roll front deposits from the Wyoming
district, with an U derived either from U-rich Archean high-K calc-alkaline granites [Stuckless
-
8/13/2019 Felsic Magmatism and U Deposits
32/62
31
& Nkomo, 1978] or from interstratified volcanic ash [Zielenski, 1983]. Similar processes apply
to the calcrete hosted deposits formed by evapotranspiration processes, with the type
example represented by the Yeelerie deposit in Western Australia [Carlisle et al., 1978]. The
relation between granites is still more direct in the case of the U-deposits of paleovalley type
from the Vitim district in Russia which occur in organic matter bearing sandstone deposited in
narrow valleys directly incised into high-K calc-alkaline granites [Kondrat'eva et al.2004].
For other uranium deposit types their relation with an igneous uranium source is more
tenuous. Large U grade differences exist between the different occurrences of black shales
and phosphorite-hosted deposits of the world. The high U content of the Cambrian Alum
shale of Sweden, compared to other occurrences, may be explained from a provenance
comprising the alteration of the U-rich Svecofennian granitic basement. Similarly the high U
content of the Moroccan phosphorites may derive from the presence of U-rich Hercynian
granite in their source area. However, no specific study has yet been carried out to confirm
such relationships.
CONCLUSIONS
Uranium deposits may derive directly and dominantly from magmatic processes in the case
of deposits related to extreme fractional crystallization of peralkaline rocks , or to partial
melting of U-rich crustal protoliths. However most deposits are related to uranium leaching by
a variety of hydrothermal and surficial fluids, much later than the emplacement of the
igneous rocks from which the uranium is derived.
Uranium enrichment above the Clarke value is necessary for a granitic or volcanic rock to
represent a viable uranium source for the formation of uranium deposits, but is not sufficient.
In addition, however, uranium has to be hosted in a site from which it can be leached by
oxidized hydrothermal fluids or ground waters. Uraninite represent the most easily leachable
uranium source it occurs mainly in highly fractionated peraluminous leucogranite and
related pegmatites, in weakly peraluminous anatectic pegmatoids resulting from low degree
-
8/13/2019 Felsic Magmatism and U Deposits
33/62
32
of partial melting of metasedimentary rocks and less commonly in highly fractionated high K
metaluminous granite and related pegmatites. U hosted in silicates, such as uranothorite,
allanite, U-rich zircon and Nb, Nb-Ti oxydes can be leached easily only when the structure of
these minerals becomes metamict. Leaching of uranium from other accessory minerals like
monazite is generally not possible other than under exceptional conditions such as the
hydrothermal diagenetic deposits related to Proterozoic unconformities, where highly saline,
acidic and relatively hot oxidized diagenetic fluids circulate.
Further research is needed to clarify a series of questions concerning the relations between
felsic igneous rocks and uranium deposits. A crucial point is the understanding of the
mechanisms leading to the genesis of Mesoarchean high-K granites able to crystallize
uraninite and containing uranium contents similar to those reached during later geologic
times. The genesis of uranium mineralization at Olympic Dam - the world largest uranium
deposit - would require a systematic study of the distribution of uranium within the deposits,
in relation to the tectonic structures and the redox zonation, and a precise dating of the
different generations of uranium minerals. At the mineral scale a better quantification of thetime required for the metamictisation of uranothorite, and hence its ability to act as a viable
source of uranium in secondary deposits, is also required so that the role that high K calc-
alkaline granites play in uranium fertilization is better known.
Remerciements: Je tiens remercier tous les collgues du CREGU et des socits
minires et en particulier de COGEMA puis AREVA pour leur soutien et leur collaboration
pour la ralisation des travaux de recherche qui ont conduit cette synthse. Ce papier a
bnfici des relectures critiques et de suggestions de Maurice Pagel et de Laurence Robb.
-
8/13/2019 Felsic Magmatism and U Deposits
34/62
33
REFERENCES
ADAMEK P.M.&WILSON M.R.(1977). - Recognition of a new uranium province from the
Precambrian of Sweden. - Proceedings Technical Committee, Vienna, IAEA, 199-215.
ADAMS S.S.&CRAMER R.T. (1985). - Data-process-criteria model for roll-type uranium
deposits. - Geological Environments of Sandstone-Type Uranium Deposits, IAEA, Vienna,
(1985): IAEA-TECDOC-328, 383-400.
AHAMDACH N.,PAGEL M.&MATHISV. (1993). - Les inclusions vitreuses dans les cristaux
d'apatite des cinrites permiennes du basin uranifre de Lodve. - C. R. Acad. Sci. [Paris],
316, 929-936.
ALEXANDREP. (2010). - Mineralogy and geochemistry of the sodium metasomatism-related
uranium occurrence of Aricheng South, Guyana. - Mineral. Dep., 45, 351-367.
ANDERSSONA.,DAHLMAN B.,GEE D.G.&SNLL S. (1985). - The Scandinavian Alum Shales. -
Sveriges Geolog. Unders., Serie Ca: Avhandlingar och UppsatserI A4, NR56, 50 p.
ANNESLEY I.R.&MADORE C. (1999). - Leucogranites and pegmatites of the sub-Athabasca
basement, Saskatchewan: U protore ? In : Mineral Deposits: Processes to Processing.
STANLEYC.J. et al., Eds., Balkema, 1, 297300.
BALASHOVY.A. (1968). - The geochemistry of the Lovozero alkaline massif. -Australian Natl.
Univ. Press, Canberra, 395 p.
BASSON I.J.&GREENWAYG. (2004). - The Rssing Uranium Deposit: a product of late-
kinematic localization of uraniferous granites in the Central Zone of the Damara Orogen,
Namibia. - J. African Earth Sci., 38, 413435.
BERNARD-GRIFFITHS J.,PEUCAT J.J.,SHEPPARD S.&VIDAL P. (1985). - Petrogenesis of
Hercynian leucogranites from the southern Armorican Massif: contribution of REE and
-
8/13/2019 Felsic Magmatism and U Deposits
35/62
34
isotopic [Sr, Nd, Pb and O] geochemical data to the study of source rock characteristics and
ages. - Earth Planet. Sci. Lett., 74, 235-250.
BERNING J.,COOKE R.,HIEMSTRA S.A.&HOFFMAN U. (1976). - The Rssing uranium deposit.
South West Africa. - Econ. Geol., 71, 351368
BLICHERT-TOFT J.,AMDT N.T.&LUDDEN J.N. (1996). - Precambrian alkaline magmatism. -
Lithos, 37, 97111.
BOHSE H.,ROSE-HANSEN J.,SRENSEN H.,STEENFELTA.,LOVBORG L.&KUNZENDORF H.
(1974). - On the behavior of uranium during crystallization of magmas with special
emphasis on alkaline magmas In Formation of Uranium Ore Deposits. Internat. Atomic
Energy Agency, Vienna, 49-60.
BOURGUIGNONA. (1988). - Origine des formations paradrives et orthodrives acides du
Limousin central. Une source possible pour les leucogranites uranifres. - Unp. PhD thesis,
Lyon, 208 p.
BOWDEN P.&TURNER D.C. (1974). - Peralkaline and associated ring-complexes in the
Nigeria Niger Province, West Africa. In: The Alkaline Rocks, J. SRENSEN, Eds., John
Wiley and Sons, New York, 330-352.
BOWRING,S.A.&HOUSH T. (1995). - The Earths early evolution. - Science, 269, 15371540
BOYLED.R. (1982). - The formation of basal-type uranium deposits in South Central British
Columbia. - Econ. Geol. 77, 1176-1209.
BROUAND M.,CUNEY M.&DELOULE E. (2003). - Eastern extension of the Taltson orogenic
belt and eastern provenance of Athabasca sandstone: IMS 1270 ion microprobe U/Pb dating
of zircon from concealed basement plutonic rocks and from overlying sandstone [Canada].
In: CUNEYM. Ed., ProceedingsIntern. Conf.,Uranium Geochemistry 2003, April 13-16,
2003. - Universit Henri Poincar, Nancy, France, 91-94.
-
8/13/2019 Felsic Magmatism and U Deposits
36/62
-
8/13/2019 Felsic Magmatism and U Deposits
37/62
36
CHERNYSHEV I.V.&GOLUBEVV.N. (1996). - The Strel'tsovskoe deposit, Eastern
Transbaikalia: isotope dating of mineralisation in Russia's largest uranium deposit. -
Geokhim., 10, 924-937 [in Russian].
CINELU S.&CUNEYM. (2006). - Na-metasomatism and UZr mineralization: A model based
on the Kurupung batholith [Guyana]. Goldschmidt Conf, Melbourne, Australia. Geochim.
Cosmochim. Acta., 70, A103.
CLEMENSJ.D., Belchery R.W. & Kisters A.F.M. (2010). - The Heerenveen Batholith,
Barberton Mountain Land, South Africa: Mesoarchaean, Potassic, Felsic Magmas Formed by
Melting of an Ancient Subduction Complex. J. Petrol., 51, 1099-1120.
CREASER,R.A. (1996). - Petrogenesis of a Mesoproterozoic quartz latite-granitoid suite from
the Roxby Downs area, South Australia. - Precamb. Res.,79, 371-394.
CUNEYM. (1978). - Geologic environment, mineralogy, and fluid inclusions of the Bois Noirs-
Limouzat uranium vein, Forez, France. Econ. Geol., 73,1567-1610.
CUNEYM. (1980). - Preliminary results on the petrology and fluid inclusions of the Rssing
uraniferous alaskites. Trans. Geol. Soc. South Africa, 83, 39-45.
CUNEYM. (1982). - Processus de concentration de l'uranium et du thorium au cours de la
fusion partielle et de la cristallisation des magmas granitiques.- In: OCDE, Paris, Ed.,Les
mthodes de prospection de l'uranium, 277-292.
CUNEYM. (1990). - Contrles magmatiques et structuraux de la mtallogense uranifre
tardi-hercynienne ; exemple du district de la Crouzille [Haute-Vienne]. Chron. Rech. Min.,
499, 9-17.
CUNEYM. (2009). - The extreme diversity of uranium deposits. Miner. Dep., 44, 39.
CUNEYM. (2010). - Evolution of uranium fractionation processes through time: driving the
secular variation of uranium deposit types. - Econ. Geol., 105, 449-465.
-
8/13/2019 Felsic Magmatism and U Deposits
38/62
37
CUNEY M. (2011). - Uranium and thorium: The extreme diversity of the resources of the
worlds energy minerals. In: R. Sinding-Larsen and F.-W. WELLMEREds., Non-Renewable
Resource Issues: Geoscientific and Societal Challenges, International Year of Planet Earth,
Springer, 91-129
CUNEY M.(2013).Uranium and Thorium Resources and Sustainability of Nuclear Energy, in
P. Burns editor, Uranium: Cradle to Grave, MAC Short Course Series43, 15,417-438.
CUNEY M.&FRIEDRICH M.(1987). - Physicochemical and crystal-chemical controls on
accessory mineral paragenesis in granitods. Implications on uranium metallogenesis. - Bull.
Minral., 110, 235-247.
CUNEY M.&MATHIEUR. (2000). - Extreme Light Rare Earth Element mobilization by
diagenetic fluids in the geological environment of the Oklo natural reactor zones, Franceville
basin, Gabon. - Geology, 28, 743-746.
CUNEY M.&KYSER K. (2008). - Recent and not-so-recent developments in uranium deposits
and implications for exploration. - Mineral. Assoc. Canada, Short Course Series39, 257 p.
CUNEY M.,FRIEDRICH M.,BLUMENFELD P.,BOURGUIGNONA.,BOIRON M.C.,VIGNERESSE J.L.,
&POTYB. (1989). - Metallogenesis in the French part of the Variscan orogen. Part I : U-
preconcentrations in the pre-Variscan and Variscan formations - A comparison with Sn, W
and Au. - Tectonophysics, 177, 39-57.
CUNEY M.,EMETZA.,MERCADIER J.,MYKCHAYLOV V.,SHUNKO V.,&YUSLENKOA. (2012). - U
deposits associated with sodium metasomatism from Central Ukraine: a review of some of
the major deposits and genetic constraints. - Ore Geology Review, 44, 82-106.
DAVIS J.&HAWKESWORTH C. (1993). - The petrogenesis of 3020 Ma basic and intermediate
volcanics from the Mogollon-Datil Volcanic Field, New-Mexico, USA. Contrib. Mineral.
Petrol., 115, 165183.
-
8/13/2019 Felsic Magmatism and U Deposits
39/62
38
DEBON F.&LEFORT P. (1988). - A cationic classification of common plutonic rocks and their
magmatic associations: principles, method, applications. - Bull. Minral., 111, 493-510.
DELPIN M.,FRIMMEL H.E.,EMSBO P.,KOENIGA.E.&KERN M. (2013). - Trace element
distribution in uraninite from Mesoarchaean Witwatersrand conglomerates [South Africa]
supports placer model and magmatogenic source. - Mineral. Dep., 48, 423-435
DEROME D.,CATHELINEAU M.,CUNEY M.,FABRE C.&LHOMME T. (2005). - Evidences of brine
mixing in the McArthur River unconformity-type uranium deposit [Saskatchewan, Canada].
Implications on genetic models. Econ. Geol., 100, 1529-1545.
de WITM.J. (1998). - On Archean granites, greenstones, cratons and tectonics: Does the
evidence demand a verdict? - Precamb. Res., 91, 181226.
de WIT M.J.,ROERING C.,HART R.J.,ARMSTRONG R.A.,DE RONDE C.E.J.,GREEN R.W.E.,
TREDOUX M.,PEBERDY E.&HART R.A. (1992) - Formation of an Archean continent: Nature, v.
357, p. 553562.
Drouet, S. (2012). - Minralogie et gochimie des pegmatodes minraliss en uranium du
Nord Qubec. Master Univ. Lorraine, Nancy., 47 p.
DRPPEL K.,MCCREADYA.J.&STUMPFL,E.F. (2009). - High-K granites of the Rum Jungle
Complex, N-Australia: Insights into the Late Archean crustal evolution of the North Australian
craton. - Lithos, 111, 203219.
DUHAMEL I.,CUNEY M.,&VAN LICHTERVELDE M. (2009). - First characterization of uraninite in
an Archean peraluminous granitic pegmatite at Tanco [Manitoba, Canada]. Inference for
uraninite placer deposits. - [abs.], Geological Association of Canada-Mineralogical
Association of Canada Conference, Qubec, Canada, 33, 50.
EBYG.N. (1992). - Chemical subdivision of the Atype granitoids: Petrogenetic and tectonic
implications. Geology,20, 641-644.
-
8/13/2019 Felsic Magmatism and U Deposits
40/62
39
FAYEK M.,&KYSERK.K. (1997). - Characterization of multiple fluid events and rare-earth-
element mobility associated with formation of unconformity- type uranium deposits in the
Athabasca Basin, Saskatchewan. Canad. Mineral., 35, 627-658.
FORBES P.,PACQUETA.,CHANTRET F.,OUMAROU J.&PAGEL M. (1984). - Marqueurs du
volcanisme dans le gisement duranium dAkouta [Rpublique du Niger]. C. R. Acad. Sci.,
Paris, 298, 647-650.
FRAENKEL M.O.,SANTOS R.C.DOS,LOUREIRO,F.E.V.DE V.L.&MUNIZ W.S. (1985). - Jazida
de urnio no Planalto de Poos de Caldas Minas Gerais. - Captulo V . In: Ministrio das
Minas e Energia - Recursos Minerais Energticos Departamento Nacional da Produo
Mineral - Companhia Vale do Rio Doce. Volume I. Principais Depsitos Minerais do Brasil.
Braslia, 89-103.
FRIEDRICH M.,CUNEY M.&POTY B. (1987). - Uranium geochemistry in peraluminous
leucogranites. - Uranium, 3, 353-385.
FRIMMEL H.E.,GROVES D.I;,KIRK J.,RUIZ J.,CHESLEY J.&MINTER W.E.L. (2005). - The
formation and preservation of the Witwatersrand goldfields, the largest gold province in the
world. In: J.W. Hedenquist, J.F.H. Thompson, R.J. Goldfarb, & J.P. Richards Eds. - 100th
Anniv Vol, Society Econ Geol., 9, 769-797.
FROST C.D.,FROST B.R.,CHAMBERLAIN K.R.,&HULSEBOSCH T.P. (1998). - The Late Archean
history of the Wyoming province as recorded by granitic magmatism in the Wind River
Range, Wyoming. - Precamb. Res., 89, 145173.
GABOREAU S.,CUNEY M.,QUIRT D.,BEAUFORT D.,PATRIER P.&MATHIEUR. (2007). -
Aluminium Phosphate Sulfate minerals associated with Proterozoic unconformity-type
deposits in the Athabasca basin, Canada. Amer. Mineral., 92, 267-280.
-
8/13/2019 Felsic Magmatism and U Deposits
41/62
40
GAUTHIER-LAFAYEF. (1986). - Les gisements d'uranium du Gabon et les racteurs d'Oklo.
Modle mtallognique de gites fortes teneurs du Protrozoique infrieur. Mm. Sci. Gol.,
Strasbourg Univ., 78, 206.
GHANDIS.S. (1978). - Geological setting and genetic aspects of uranium occurrences in the
Kaipokok Bay-Big river area, Labrador. - Econ. Geol., 73, 1492-1522.
HALLBAUERD.K. (1984). - Archean granitic sources for detrital mineral assemblage in the
Witwatersrand conglomerates [abs.]. - Geocongress 84, Geol. Soc. South Africa,
Potchefstroom, 5356.
HATTORI K.,HART S.R.,&SHIMIZUN., (1996). - Melt and source mantle compositions in the
Late Archaean: A study of strontium and neodymium isotope and trace elements in
clinopyroxenes from shoshonitic alkaline rocks. - Geochim. Cosmochim. Acta, 60, 4551-
4562.
HANSLEY P.L.&SPIRAKISC.S. (1992). - Genesis of tabular uranium-vanadium deposits in the
Morrison Formation, Colorado Plateau. Econ. Geol., 87, 352-365.
HECHT L.&CUNEY M. (2000). - Hydrothermal alteration of monazite in the Precambrian
basement of the Athabasca Basin: implications for the genesis of unconformity related
deposits. - Mineral Dep., 35, 791-795.
HITZMAN M.W.&VALENTAR.K. (2005). - Uranium in Iron Oxide-Copper-Gold [IOCG]
systems. Econ. Geol., 100,1657-1661.
HITZMAN M.W.,ORESKES N.&EINAUDI M.T. (1992). - Geological characteristics and tectonic
setting of Proterozoic iron oxide [Cu-U-Au-LREE] deposits. Precamb. Res., 58, 241 287
IAEA (2001). - Analysis of Uranium Supply to 2050, STI-PUB-1104, IAEA, Vienna, 156 p.
-
8/13/2019 Felsic Magmatism and U Deposits
42/62
41
IAEA (2006). - Global and Identified Resources. Nuclear Development Forty Years of
Uranium Resources Production and Demand in Perspective, The Red Book Retrospective,
NEA/OCDE IAEA, Vienna, 279 p.
IAEA (2009). - Uranium 2009 Resources, Production and Demand. NEA/OCDE IAEA,
Vienna, 454 p.
JAVOYM., (1998). - The birth of the Earths atmosphere: the behaviour and fate of its major
elements. - Chem. Geol., 147, 1125.
JAYANANDA M.,MOYEN J.-F.,MARTIN H.,PEUCAT J.-J.,AUVRAY B.&MAHABALESAWAR B.
(2000). - Late Archaean (25502520 Ma) juvenile magmatism in the eastern Dharwar craton,
southern India: Constraints from geochronology, Nd-Sr isotopes and whole rock
geochemistry. - Precamb. Res., 99, 225254.
JOHNSON J.P.&MCCULLOCHM.T. (1995). - Sources of mineralizing fluids for the Olympic
Dam deposit [South Australia]: Sm-Nd isotopic constraints. Chem. Geol., 121, 177-199.
JOHNSON J.P.&CROSSK.C. (1995). - U-Pb geochronological constraints on the genesis of
the Olympic Dam Cu-U-Au-Ag deposit, South Australia. Econ. Geol., 90, 1046-1063.
KINNY P.D.&NUTMANA.P. (1996). - Zirconology of the Meeberrie gneiss, Yilgarn craton,
Western Australia: An early Archean migmatite. Precamb. Res., 78, 165178.
KONDRAT'EVA I.A.,MAKSIMOVA I.G.&NADYARNYKHG.I. (2004). - Uranium Distribution in Ore-
Bearing Rocks of the Malinov Deposit: Evidence from Fission Radiography. Litholog.
Mineral. Res., 39, 333-344.
KOTZER T.&KYSER T.K. (1995). - Fluid history of the Athabasca Basin and its relation to
diagenesis, uranium mineralization and paleohydrology. - Chem. Geol., 120, 45-89.
KUMAR P.S.&REDDYG.K. (2004). - Radioelements and heat production of an exposed
Archaean crustal cross-section, Dharwar craton, south India. E.PS.L., 224, 309-324.
-
8/13/2019 Felsic Magmatism and U Deposits
43/62
42
KYSER K.,HIATT E.,RENAC C.,DUROCHER K.,HOLK G.&DECKARTK. (2000). - Diagenetic
fluids in Paleo- and Mesoproterozoic sedimentary basins and their implications for long
protracted fluid histories, Chapter 10. In: KYSER, K., Ed., Fluids and Basin Evolution. - Short
Course Series [Series Robert Raeside Ed.]: Mineral. Assoc. Canada, 28, 225-262.
LEROYJ. (1978). - The Margnac and Fanay uranium deposits of the La Crouzille district
[Western Massif Central, France], geologic and fluid inclusion studies. - Econ. Geol., 73,
1611-1634.
LEROY J.&GEORGE-ANIEL B. (1992). - Volcanism and uranium mineralisations: the concept
of source rock and concentration mechanism. - J. Volcan. Geotherm. Res., 50, 247-272.
LEROY J.&HOLLIGERP. (1984). - Mineralogical, chemical and isotopic [U/Pb method] studies
of Hercynian uraniferous mineralizations [Fanay and Margnac mines, Limousin, France]. -
Chem. Geol., 45, 121-134.
LINNEN R.L.&CUNEYM. (2005). - Granite-related rare-element deposits and experimental
constraints on Ta-Nb-W-Sn-Zr-Hf mineralization. In: Rare-Element Geochemistry and Mineral
Deposits. LINNEN,R.L.&SAMSON, I.M., Eds. - Geol. Assoc. Can, Short Course Notes, 17, 45-
67.
MAAS R.,MCCULLOCH M.T.,CAMPBELL I.H.,&PAGE R.W. (1987). - SmNd isotope
systematics in uraniumrare earth mineralisation at the Mary Kathleen uranium mine,
Queensland. Econ. Geol., 82, 18051826.
MACDONALDR. (1987). - Quaternary peralklaine silicic rocks and caldera volcanoes of
Kenya. In: J.G.FITTON &B.G.L.,UPTON, Eds., Alkaline Igneous Rocks. - Geol. Soc. Sp. Pub.,
30, 313-333
MACKEVETTE.A. (1963). - Geology and ore deposits of the Bokan Mountain uranium-thorium
area, southeastern Alaska. - U.S. Geol. Survey Bull.,1154, 125 p.
-
8/13/2019 Felsic Magmatism and U Deposits
44/62
43
MADORE C.,ANNESLEY I.&WHEATLEY K. (2000). - Petrogenesis, age, and uranium fertility of
peraluminous leucogranites and pegmatites of the McClean Lake / Sue and Key Lake / P-
Patch deposit areas, Saskatchewan, GeoCanada: The Millennium Geoscience Summit. -
Joint meeting Can. Geoph. Union, Can. Soc. Expl. Geoph., Can. Soc. Petrol. Geol., Can.
Well Log. Soc.,Geol. Assoc. Can, Mineral. Assoc. Can., Calgary, Alberta, 4.
MARTINH. (1994). - The Archean grey gneisses and the genesis of the continental crust.
In: K.C. CONDIE, Ed., Archean crustal evolution, Volume 11. - Developments in Precambrian
Geology, Amsterdam, Elsevier, 205-259.
MARTIN H.,MOYEN J.-F.,&RAPP R. (2010). - Sanukitoids and the Archean-Proterozoic
boundary. - Trans. R. Soc. Edinb., 100, 1533.
MCGILL B.D.,MARLATT R.B.,MATTHEWS R.B.,SOPUCK V.J.&HOMENIUK L.A. (1993). - The P2
North Uranium deposit; Saskatchewan, Canada. Expl. Mining Geol., 2, 321-331.
MCKAY D.&MIEZITISY. (2001). - Australias uranium resources, geology and development of
deposits. Mineral Resource Report 1. AGSO. - Geoscience Australia, Canberra 200 p.
MERCADIER J.,ANNESLEY I.R.,MCKECHNIE C.L.,BOGDAN T.S.&CREIGHTONS. (2013). -
Magmatic and metamorphic uraninite mineralization in the western margin of the Trans-
Hudson Orogen [Saskatchewan, Canada]: major protores for unconformity-related uranium
deposits. - Econ. Geol., 108[in press].
MONTELJ.-M. (1993). - A model for monazite/melt equilibrium and application to the
generation of granitic magmas. Chem. Geol., 110, 127-146.
MOREAU M.,POUGHONA.,PUIBARAUD Y.,&SANSELME H.(1966).Luranium et les granites.
Chron. Mines Rech. Min., 350, 47-51.
MOYENJ.-F. (2011). - The composite Archaean grey gneisses: petrological significance, and
evidence for a non-unique tectonic setting for Archaean crustal growth. - Lithos, 123, 21-36.
-
8/13/2019 Felsic Magmatism and U Deposits
45/62
44
MOYEN J.-F.,MARTIN H.,&JAYANANDA M., (2001). - Multi-element geochemical modelling of
crust-mantle interactions during late-Archaean crustal growth: The Closepet granite [South
India]. - Precamb. Res., 112, 87105.
OLIVER N.H.S.,PEARSON P.J.,HOLCOMBE R.J.&ORDA. (1999). - Mary Kathleen
metamorphic hydrothermal uranium - rare-earth element deposit: ore genesis and numerical
model of coupled deformation and fluid flow. Austral. J. Earth Sci., 46, 467-484.
PAGER.W. (1983). - Chronology of magmatism, skarn formation, and uranium